1. Field of the Invention:
The present invention relates to a control system for an electric actuator, which is capable of appropriately protecting a rotary driving source for driving the electric actuator.
2. Description of the Related Art:
In general, when an installation type industrial robot is used, a base is fixed by bolts or the like. When a tip end of the robot is excessively pressed or smashed by malfunctioning of the interlock or the like, the operation of the robot is stopped by detecting an overcurrent condition. That is, it is principally intended to prevent the robot and the workpiece from being destroyed, by detecting the overcurrent condition of the installation type industrial robot. The positional deviation of the robot itself is not taken into consideration.
In view of the above, Japanese Laid-Open Patent Publication No. 2002-66969 discloses a technical concept which is directed to prevent an automatic or unmanned transport vehicle from floating even when a tip end of a robot arm is excessively pressed to or smashed against surrounding equipment.
That is, Japanese Laid-Open Patent Publication No. 2002-66969 discloses a control apparatus which executes an operation for limiting current flowing to a servo motor for driving a joint of the robot arm if joint torque applied to the joint of the robot arm meets a predetermined limit value, when the tip end of the robot arm is moved based on attitude control and position control of the robot arm.
However, when the technical concept disclosed in the Japanese Laid-Open Patent Publication No. 2002-66969 is applied, for example, to an electric actuator for converting a rotary motion of a motor into a rectilinear motion of a slider or the like, it is necessary to provide a detector such as an encoder and a resolver, and a control circuit in order to control, for example, the position and the operation speed of the slider, in which the production cost becomes expensive.